Triacylglycerol composition of winged bean (Psophocarpus tetragonolobus)

Winged beans were extracted with hexane and the extracted lipid was analyzed by HPLC for its triacylglycerol (triglyceride) composition on a Lichrosorb RP-18 column with acetonitrile-tetrahydrofuran-dichloromethane (6:2:1) solvent mixtures. The chromatography yielded more than 21 peaks, and each triacylglycerol was analyzed for fatty acids by GLC. The major triacylglycerols were found to be behenoyl-linoleoyl-oleoylglycerol (21.3%), trioleoylglycerol (10.5%) and behenoyl-dioleoylglycerol (15.6%). Winged bean oil was found to contain triacylglycerols of larger ECN (equivalent carbon number) than soybean oil.

On-column partition cleanup of fatty extracts for organophosphate pesticide residue determination

A fast, single-step, and efficient partition between n-hexane and acetonitrile on ready-to-use, disposable mini-columns of Kieselghur-type material has been developed for the cleanup of fatty extracts for organophosphate (OP) pesticide residue determination by gas chromatography with flame photometric detection. Nine OP pesticides (diazinon, etrimfos, chlorpyrifos-methyl, pyrimiphos-methyl, chlorpyrifos, bromophos, bromophos-ethyl, malathion, fenitrothion) most commonly used for protection of stored cereals, oil seeds, and legumes were separated from up to 2.0 g lipidic material with recoveries between 80 and 107% at spiking levels ranging for the different compounds from 0.1 to 5.0 ppm.

Headspace gas chromatographic determination of residual 1,3-butadiene in rubber-modified plastics and its migration from plastic containers into selected foods

A headspace gas chromatographic procedure has been developed for the determination of 1,3-butadiene in rubber-modified plastics and in some foods. Polymer solutions or foods are equilibrated in sealed vials at 90 degrees C, and headspace samples are injected into a gas chromatograph. 1,3-Butadiene residues are measured using a flame ionization detector and are quantitated by the method of standard additions or an external calibration curve. Refrigerator tubs, vegetable oil bottles, chewing gum, and foods in contact with this type of packaging were analyzed. Limits of quantitation varied with the matrix, ranging from 2 ng/g (ppb) in chewing gum to 20 ng/g in polymers. 1,3-Butadiene was found in one polymer at 53 ng/g with an 8% coefficient of variation. The procedure yields "apparent" trace levels of 1,3-butadiene, and confirmation by a complementary technique is required.

Analytical methods for determination of neat and microencapsulated trichloroethylene in dosing vehicles and whole blood

Gas chromatographic methodologies were developed for the analysis of microencapsulated trichloroethylene (TRI) in corn oil and feed dosage formulations as well as neat TRI in corn oil and whole blood. Recovery, precision, linearity, and the appropriateness of a linear regression model were evaluated for each method. In all cases recovery was greater than 96% and linearity of the standard curves was confirmed. Good precision and chromatographic resolution were obtained for all samples analyzed.

Atherogenesis. An epidemiological model based on the presence of unnatural trans and cis isomers of unsaturated fatty acids in the maternal diet and in mothers milk

The hypothesis that the presence of unnatural trans and cis isomers of unsaturated fatty acids in the maternal diet and in human mothers milk could be responsible for initiating atherosclerosis in utero or in infants is proposed. It is suggested that the key etiological factor involved in the formation of atherosclerotic plaques could be uncontrolled division of smooth muscle cells of the intima resulting from the intracellular excess of linoleic acid and deficiency of its metabolites gamma-linolenic acid and dihomogamma-linolenic acid. This imbalance is brought about by competitive inhibition of the enzyme delta-6-desaturase by unnatural trans and cis unsaturated fatty acids. Delta-6-desaturase is the enzyme responsible for converting linoleic acid to dihomogamma-linolenic acid. The cellular presence of unnatural trans and cis isomers of unsaturated fatty acids would therefore enhance increased levels of linoleic acid and deficiency of its metabolites gamma-linolenic acid and dihomogamma-linolenic acid. It is proposed that prophylaxis against the effects of delta-6-desaturase inhibition could be achieved by the adoption of an Eskimo-like diet containing the essential fatty acid metabolites gamma-linolenic acid and/or dihomogamma-linolenic acid and eicosapentaenoic acid per se in high concentrations.

Natural occurrence of Alternaria mycotoxins in olives--their production and possible transfer into the oil

A limited survey of the natural occurrence of the major Alternaria mycotoxins, i.e. alternariol (AOH), alternariol methyl ether (AME), altenuene (ALT), altertoxin-I (ATX-I), and tenuazonic acid (TA) has been carried out on olives and related processing products (oil and husks). The toxigenicity of Alternaria strains isolated from olives and the possible mycotoxin transfer into the oil have also been investigated. Four out of 13 olive samples were contaminated by 2 to 4 Alternaria mycotoxins. The highest contamination was found in a badly damaged sample containing 2.9, 2.3, 1.4 and 0.3 mg/kg of AME, AOH, ALT and TA, respectively. No mycotoxins were detected in olive-oil destined for human consumption (6 samples) or olive-husks (3 samples) collected from oil-mills after the first pressing of olives. An oil sample produced in our laboratory by processing the most contaminated olive sample contained AME (0.79 mg/kg) and AOH (0.29 mg/kg). The estimated mycotoxin amount transferred into the oil was 4% for AME, 1.8% for AOH, and zero for ALT and TA (considering 15% the oil yield). Although Alternaria species, mostly A. alternata (Fr.) Keissler, were present at various extent on all the examined olive samples, mycotoxins were only detected in samples of physically damaged olives. The production of mycotoxins by A. alternata isolated from olives was much higher (up to 3 order of magnitude for TA) on rice cultures than on olive cultures.

Detection of olive oil adulteration with linoleic acid-rich oils by reversed-phase high-performance liquid chromatography

Adulteration of olive oil with very low levels (1-2%) of linoleic acid-rich oils can be unequivocally detected by reversed-phase high-performance liquid chromatography on columns packed with C18 alkyl bonded-phase particles. Triglyceride fractionation according to their equivalent carbon numbers is effected in 22-25 min by eluting the column with a non-aqueous mobile phase (acetonitrile-absolute ethanol-isopropanol, 72:18:10), compatible with UV-detector systems.

Qualitative and quantitative analysis of peanut oil triacylglycerols by reversed-phase liquid chromatography

Triacylglycerols (TGs) from an african peanut oil were analysed and fractionated by reversed-phase liquid chromatography (RPLC) using a differential refractometer as a detector. The fatty acids of the 33 collected fractions were analysed by gas chromatography after pentadecanoic acid (15:0) was added as an internal standard to quantitate the TG fractions. The three major fatty acids in the oil were octadecenoic acid (oleic acid, 44.5%), octadecadienoic acid (linoleic acid, 32.3%) and hexadecanoic acid (palmitic acid, 13.9%) together amounting to ca. 90% of the total fatty acids. Very long-chain saturated fatty acids (20:0-26:0) were also found. Thirty TGs could be easily identified from the fatty acid composition of the fractions alone. Dioleoyllinoleoylglycerol (18:1, 18:1, 18:2) was the main TG, amounting to nearly 17% of the oil, followed by palmitoyloleoyllinoleoylglycerol (16:0, 18:1, 18:2) (13%), oleoyldilinoleoylglycerol (18:2, 18:2, 18:1) (12%) trioleoylglycerol (18:1, 18:1, 18:1) (10%) and palmitoyldioleoylglycerol (16:0, 18:1, 18:1) (8%). These five TGs, which were virtually the only TGs in their respective fractions, together represented ca. 60% of the peanut oil TGs. Straight parallel lines were found for different series of TGs on plotting the logarithm of the relative retention time of the identified TGs (and those further identified) versus the number of double bonds. Other straight parallel lines were also observed on plotting the carbon numbers versus the equivalent carbon numbers of the oil TGs. These linear relationships were used to predict the different TGs present in the complex fractions. Their proportions in most instances were easily determined from the fatty acid composition of the fractions. In a very few instances a mathematical method had to be applied to solve the problem. Using the above-mentioned methods, 84 TGs could be identified and their percentages determined in the studied peanut oil. The very long-chain saturated fatty acids were always found associated with unsaturated fatty acids, preferentially with two molecules of linoleic acid. On the other hand, correction factors, determined from commercial simple TGs, were applied to peak areas before calculating the percentages of the 33 eluted TG fractions. For the major fractions of the oil, the series of values thus obtained was comparable to the series determined by the internal standardization procedure. Data reported here for peanut oil TGs are likely to be useful in identifying and quantifying the component TGs of other oils analysed by RPLC under the reported conditions.

[Peeling of sorghum by a dry method: continuous and discontinuous methods]

A study was carried out wherein two dry dehulling sorghum grain methods, the continuous and discontinuous types, were quantitatively compared in a laboratory abrasive dehulling device. Reflectance values, expressed as dehulling percentage, the percentage of kernels removed, and of kernel cracking were evaluated. Graphs of the dehulled and removed percentages as function of the contrast time for each method, revealed that the continuous process was the most efficient of both procedures. Analysis of the broken kernels indicated a similar behavior for both methods. The macrocomponent and tannin variations as dehulling advanced, as well as the reflectance values were determined with the continuous method. Findings showed that the greater proportion of tannin, fiber and ashes has been removed at the 85% extraction rate. Thus, abrasion of grains above the 65% extraction rate is not convenient, since an excessive loss of nutrients is produced without any important decrease in polyphenolic pigments and of those imparting color to the sorghum grain milling products.

Determination of polycyclic aromatic hydrocarbons (PAH) in edible vegetable oils by liquid chromatography and programmed fluorescence detection. Comparison of caffeine complexation and XAD-2 chromatography sample clean-up

Two clean-up procedures were compared for the analysis for polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils. One method comprises a liquid-liquid extraction followed by XAD-2 chromatography and the other a caffeine-formic acid complexation. The clean-up step is followed by gradient reversed-phase HPLC in combination with wavelength-programmed fluorescence detection. Due to better repeatability and simplicity, the XAD-2 method was selected for the determination of PAHs in 14 different vegetable oils. Between the different oil samples large differences were observed in PAH concentrations. PAH concentrations in vegetable oils sampled from the Dutch market appear to be comparable with those found in other countries.

Detection of vegetable oil adulteration in ice cream

This study was to demonstrate the application of various analytical methods to the detection, identification, and quantitation of vegetable oil adulteration of ice cream. Total fat content, sterols, long- and short-chain fatty acids, vitamin E, Reichert-Meissl values, and Polenske values were measured in ice cream. All methods except total fat determination were capable of detecting vegetable oil adulteration. Sterol determination was the most effective and versatile measurement because it provided information not only on the detection and extent of adulteration but also on the possible identity of the adulterant.

Chemoprophylactic agent in schistosomiasis: 14,15-epoxygeranylgeraniol

The occurrence of all-trans (-)-14,15-epoxygeranyl-geraniol in Pterodon pubescens Benth. is established, and its prophylactic activity against infection by Schitsosma mansoni demonstrated. Two other diterpenes present in the oil are inactive.